Alternator Rpm

[Fj1200buggy]

Can anyone please tell me the ratio between alternator rpm and engine rpm?
Thanks, Erik.

[Fj1200buggy]

I am going to put a pulley on the oem alternator that drives a car alternator, I need that ratio to determine the size pulley I need.

[Mark Olson]

There are many factors involved with your question.
what engine ?
what is you max engine rpm?
etc,etc,

go out to your car (friends car) and mark the crank pulley with a chalk line , do the same to the alt pulley .
now turn crank by hand with a socket wrench for one full rotation and count how many times the alt pulley completes a full revolution.

you can now plug it into a formula that will determine rpm.

check out the Browning belts web site.

most fall into the 4-1 ratio.

[Firehawk068]

I think he is, or has built some sort of FJ powered buggy (assumption solely based on username)
If this is the case, he could still do what Mark suggested..........
Remove pickup cover on left side of crank..........
Remove alternator cover (or remove alternator, I'm not sure what is visible inside the alternator, as I've never had my cover off)

Rotate crank one revolution........................then count how many times the alternator (or alternator drive ) rotated........

[Fj1200buggy]

I was very unspecific, sorry, it is the Fj1200 and after testing it seems that the ratio is 1:1.
So im going to have a 1:1 ratio pulley from the stock generator to the new one, wich means it will spin at 9000 rpm max.

[racerrad8]

Yes, 1:1.

Randy - RPM

[Firehawk068]

Post up some pics of said contraption!

[Mark Olson]

Yeah , post some pics of what you are building.